Artillery simulator



May 2o, 1969 uRcHAcK ART ILLERY S IMULATOR May 20, 1969 H. D. cuRcHAcK 3,444,733

ARTILLERY SIMULATOR l Filed oct. v. 196e sheet 8 of 2 United States Patent Office 3,444,733 Patented May 20, 1969 U.S. Cl. 73-167 6 Claims ABSTRACT OF THE DISCLOSURE Artillery simulator apparatus to subject projectiles containing components to be tested to linear and angular accelerations. The projectile is accelerated to a desired linear velocity and entrapped by a rotating tube, which imparts to the projectile the desired angular velocity. The linear momentum of the projectile is transferred to a large mass within the tube through a wooden column, and measurement of the velocity of the large mass from the tube -allows computation of the deceleration forces on the projectile. Electrical read-out from the components within the projectile can be obtained by means of the novel construction of the rotating tube.

This invention relates to an apparatus for simulating the linear and angular accelerations to which projectiles are subjected in rifled artillery weaponry.

The fuzes employed in modern day projectiles are conventionally battery powered. If the battery is to be stored for a long period of time the battery electrolyte may be contained in a sealed ampule to prevent degeneration of the battery charge. The electrolyte ampule is arranged to break upon the tiring of the projectile so that electrolyte is supplied immediately to the battery, thereby activating the electrical circuit of the projecticle fuze. In designing such an apparatus it is important to know the stresses and strains to which a projectile is subjected during tiring in order that the ampule may be designed to break at the correct time. Many projectiles also contain electronic components such as transmitters which contain relatively fragile parts which must be appropriately protected from excessive shocks. In order to provide the requisite protection it is necessary to know the exact degree of strain and shock to which such components may be subjected.

Various devices and methods have been proposed in the past to provide a laboratory environment similar to the actual forces experienced by a projectile. Centrifuges, spinners, air or gas guns, actuators and rocket sleds have been constructed for laboratory simulation of the forces eX- perienced by fuzes or fuze components when being launched or tired. Gas guns and spinners are the most frequently used devices -by test engineers concerned with the environment to which spinning artillery fuzes are subjected. In one gas gun technique the fuze is accelerated slowly to a predetermined velocity, and then is decelerated violently upon impact with a known target. The violent deceleration simulates the actual acceleration or set back of the iield-Iired projectile. This technique is valuable since the fuze is available immediately for inspection, and problems and costs associated with recovering a projectile actually iired in the iield are eliminated.

Fuzes may be rotated in spinners at the angular velocity produced by the actual weapon of interest and observations made of the performance of the fuze in such environment. These observations may be made by optical or electrical techiques while the fuze is spinning. Some spinners also use low inertia motors or other means in an effort to duplicate the angular acceleration experienced in actual performance in the eld.

The primary obejct of this invention is to unite the features of the gas gun and the low inertia spinner in a test apparatus to simulate the linear and angular accelerations experienced in ried artillery weaponry.

In accordance with the features of this invention an artillery simulator apparatus is provided to subject test projectiles to forces similar to the linear and angular accelerations present during actual tiring conditions. The apparatus comprises a test projectile means having a hollow body portion adapted to contain battery, mechanical or electronic components to be tested. A gas gun means is provided for accelerating the test projectile to a desired linear velocity. A rotating tube, which rotates at the desired angular test velocity, is positioned in alignment with the gas gun projectile accelerating means to catch the projectile as it is iired from the gas gun. The rotating tube contains a column of wooden blocks terminating in a heavy member having a sizeable mass. When the test projectile impacts against the wooden column, the projectile remains within the rotating tube while the heavy member is driven out the opposite end. From the mass and velocity of the projectile, the velocity attained by the heavy member and the characteristics of the wood, the linear deceleration force can be computed. This linear deceleration force is similar to the actual linear acceleration force experienced under tiring conditions, while the rotational forces of the rotating tube simulate the angular acceleration forces of actual firing.

Electrical read-out from the components under test within the projectile can be accomplished by means of the novel construction of the rotating tube. Two or more electrically insulated conductive sections are provided within the tube and are connected to external slip rings and brushes leading to appropriate instrumentation devices. The test projectile is provided with externally eX- posed contacts to which are connected leads from the test components within. These contacts engage the conductive sections within the rotating tube while the projectile is being rotated. In this fashion suitable observations can be made of the components contained within the projectile while it is under test within the tube. Rotation of the tube can be continued indeiinitely while test components are analyzed under centrifugal forces similar to those produced during projectile iiight.

The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of a preferred embodiment of the invention, as illustrated in the accompanying drawings in which:

FIG. 1 is a diagrammatic representation of a complete system embodying the principles of the present invention;

FIG. 2 is a cross-sectional view of the rotating tube comprising the spin-catch means of the present invention;

FIG. 3 is a cross-sectional view of the rotating tube taken along lines 3 3 of FIG. 2;

FIG. 4 is a perspective view of the test projectile means having a portion broken away to expose the interior contents thereof; and

FIG. 5 is a cross-sectional view of the contact structure carried by the test projectile of FIG. 4.

The invention will be understood more readily by referring to FIG. l which shows the entire system in diagrammatic form. A pressure source 1 is connected to a driver tank 3 positioned to provide the motive force to propel test projectile 5 along the length of the projectile accelerating gun 7. A restraining member 9 holds projectile 5 in position until tiring time. A vacuum pump 10 is connected through line 11 to the driver tank 3 and gun 7, and valves 13 and 15 provide the necessary control. Atmospheric pressure can be used to propel the test projectile 5 down gun barrel 7 by sealing olf the muzzle end 16 of the barrel 7 with a cellophane diaphragm and evacuating the interior. When this is done the atmospheric pressure 3 acting on the rear surface of test projectile 5 furnishes the necessary motive power.

A spin-catch assembly 17 is positioned in alignment with gun 7 so that the test projectile 5 enters the open end 35 of the spin-catch assembly 17 as it emerges from the end of gun 7. A photocell device 19 is utilized in the measurement of the linearvelocity of the test projectile 5 before it enters the spin-catch assembly 17. The spincatch assembly 17 is rotatably driven by means of drive motor 21 connected thereto by means of belt 23. For the sake of clarity in explanation the supporting structure, which may be conventional in nature, is omitted from the showing of FIG. l.

The interior of spin-catch assembly 17 contains a plurality of wooden blocks 25 disposed in longitudinal alignment and compacted relationship. A heavy member 27 is disposed immediately behind the lwooden blocks 25.

The structure of the spin-catch assembly 17 (FIG. 2) comprises an outer metallic shell 29 having end ange members 31 and 33. Flange 31 is bolted to a cylindrical section 35 which has mounted thereon a pair of slip rings 37 and 39 on which electrical brushes 41 and 43 ride. Slip ring 37 is electrically connected by means of lead 45 to a semi-cylindrical conductive member 47 in concentrically mounted relationship to metallic shell 29 and insulated therefrom by insulation 49. Similarly, slip ring 39 is electrically connected by means of lead 51 to the semi-cylindrical conductive member 53 which is mounted in concentric relationship to outer metallic shell 29 and spaced from shell 29 and semi-cylindrical conductive member 47 by means of the insulation 49.

The right end of spin-catch assembly 17 has a cylindrical member 55 attached thereto at ange 33. The cylindrical members 35 and 55 have suitable bearings 57 and 59, respectively, to enable rotation of spin-catch assembly 17, although the remaining supporting structure to accomplish such rotation has been omitted to simplify the illustration.

The details of test projectile 5 will be seen from the partially broken away perspective view of FIG. 4. The interior of test projectile 5 is hollow and contains the test component 61 undergoing evaluation. It is assumed for the purpose of this discussion that the component 61 is an electrical component, and electrical leads 63 and 65 are connected from test component 61 to the contact assembly blocks `67 and 69. Within the contact assembly blocks 67 and 69 are disposed suitable force-actuated contact members, such as contact member 71 shown in FIG. 5. Contact member 71 is positioned in block 69 at an angle so that acceleration to the right, as shown in FIG. 5, will cause contact pin 71 to be forced back in contact block 69 and not protrude therefrom. Deceleration of contact block 69 in a rightward direction, which is the equivalent of applying a force to the left, will cause contact pin 71 to be forced downwardly and protrude from contact block 69. Similarly, contact pin 71 will be caused to protrude from contact block 69 under the influence of centrifugal force, as produced by the rotation of test projectile 5.

In operation drive motor 21 rotates spin-catch assembly 17 at a predetermined angular velocity` The test projectile 5 is accelerated through gas gun 7 by means of atmospheric pressure. In either case the vacuum pump is used to evacuate gas gun 7. The linear velocity of test projectile 5 is measured by the photocell device 19 just before the projectile 5 enters the spin-catch assembly 17. In the spin-catch assembly 17 test projectile 5 impacts -against the wooden blocks 25 and the forward linear motion is decelerated to a complete stop Within the spin-catch assembly 17, thereby rapidly acquiring the angular velocity of the spin-catch assembly 17. The force of impact accelerates heavy member 27 out the opposite end of spin-catch assembly 17, and the linear velocity of member 27 is measured by the photocell device 75. Heavy member 27 is brought to rest in catch-box 77.

The force of impact of test projectile 5 and the centrifugal force produced by rotating spin-catch assembly 17 cause the electrical contacts in contact blocks 67 and 69 of test projectile 5 to engage the conductive sections 47 and 53 of spin-catch assembly 17. Suitable instrumentation is electrically connected to brush members 41 and 43, and a direct monitoring of the test component 61 can thereby be effected. When there is relative rotation between the test projectile 5 and spin-catch assembly 17, such rotation can be measured by the number of electrical current reversals occurring as one contact member passes rst from semicylindrical member 47 to semi-cylindrical member 53 and the other contact member passes from semi-cylindrical 53 to semi-cylindrical member 47 in continuing fashion. It will be appreciated at this point that a larger number of electrical leads, such as 63 and 65, may be connected to test component 61 if it becomes desirable to measure a larger number of characteristics within the component. When more than two electrical leads to the test component 61 are required, a corresponding number of electrically conductive segments must be disposed in insulated relationship around the interior of spin-catch assembly 17, and a corresponding number of electrical slip rings and brushes would be required. In practice it is most likely that a larger number of leads, etc., would be employed, but only two have been shown in order to simplify the illustration.

The impact which decelerates test projectile 5 simulates the acceleration of an actual projectile when red from the barrel of a gun. The angular acceleration produced as test projectile 5 achieves the angular velocity of spincatch assembly 17 simulates the actual spinning forces produced as a projectile is red and caused to spin by the barrel riing. The novel structure of the spin-catch assembly 17 and test projectile 5 enable electrical readout from the test component 61 under the actual conditions of impact and spinning such as would be encountered in the actual ring of a projectile. The measured physical constants and velocities provide the requisite data to calculate the acceleration and deceleration forces involved.

It will be appreciated from the foregoing description that this invention has provided a novel artillery simulator which combines the features of the conventional gas guns and low inertia spinners in a test apparatus which simulates the linear and angular accelerations experienced in rifled artillery weaponry.

While the invention has been shown and described with particular reference to a preferred embodiment, it will be understood by those skilled in the art that various changes in form and details may be made without departing from the spirit and scope of the invention.

What is claimed is:

1. An artillery simulator apparatus for subjecting test projectiles to linear and angular accelerations similar to actual firing conditions comprising:

(a) projectile means having a hollow body portion adapted to contain test components,

(b) acceleration means for accelerating said projectile means to a desired velocity,

(c) spin-catch means positioned with respect to said acceleration means to receive said projectile means when said projectile means leaves said acceleration means at the desired velocity,

(d) rst means to measure the linear velocity of the projectile means before the projectile means enters the spin-catch means,

(e) means for rotating said spin-catch means, and

(f) deceleration means positioned within said spincatch means to provide a violent deceleration reaction to said projectile means when said projectile means enters said spin-catch means,

(g) whereby components to be tested may be placed within said projectile means to be subjected to the linear and angular forces produced by said deceleration means and the means for rotating said spincatch means, such forces corresponding respectively to the linear and angular accelerating forces produced in the actual ring of a projectile.

2. The combination according to claim 1 comprising second means to measure the linear velocity of the deceleration means after deceleration ofthe projectile means.

3. The combination according to claim 2 wherein said first and second means to measure include photocell devices.

4. An artillery simulator apparatus for subjecting test projectiles to linear and angular accelerations similar to actual ring conditions comprising:

(a) projectile means having a hollow body portion adapted to contain test components,

(b) acceleration means for accelerating said projectile means to a desired velocity,

(c) spin-catch means positioned with respect to said acceleration means to receive said projectile means when said projectile means leaves said acceleration means at the desired velocity, said spin-catch means having at least two electrically insulated conductive sections,

(d) means for rotating said spin-catch means, and

(e) deceleration means positioned within said spincatch means to provide a violent deceleration reaction to said projectile means when said projectile means enters said spin-catch means,

(f) whereby components to be tested may be placed within said projectile means to be subjected to the linear and angular forces produced by said deceleration means and the means for rotating said spin-catch means, such forces corresponding respectively to the linear and angular accelerating forces produced in the actual firing of a projectile. 5. The combination according to claim 4 wherein said projectile means comprises at least two contact elements for making electrical contact with said electrically insulated conductive sections, whereby external electrical readout can be accomplished from test components within said projectile means. 6. The combination according to claim 5 wherein said deceleration means comprises a plurality of wooden blocks and a heavy member.

References Cited UNITED STATES PATENTS 2,537,096 l/1951 ShICSVe et al. 73-167 XR 2,604,777 7/1952 Armstrong et al. 73-167 XR 2,655,033 10/1953 Burrell 73-167 XR 2,891,398 6/1959 Hughes 73--167 XR 2,971,367 2/1961 Shirldledecker 73--5 3,024,652 3/1962 BIOSS 73-167 3,329,014 7/1967 Stewart Q.- 73-167 LOUIS R. PRINCE, Primary Examiner.

J. NOLTON, Assistant Examiner. 

